Bird of a different feather

Abstract

During the COVID-19 lockdown we had more opportunities to observe biodiversity around our homes. On one occasion, I observed a common Indian house crow (Corvus splendens) with uncommon white patches on its plumage, quite unlike the characteristic black body and gray neck of most house crows. The white patches distinguished the crow from hundreds of other members of its species thriving in the area. This crow’s atypical plumage was due to a congenital genetic condition called leucism, a partial or complete loss of coloration. Leucistic birds retain the normal color of their eyes and beak but may exhibit various degrees of reduced pigmentation in their feathers or skin. Leucism differs from albinism in that the former is controlled by a single recessive allele while the latter is associated with several genes. It has also been associated with the expression of mutant alleles or deviations of gene expression that disrupt pigmentation during feather development. The incidence of leucism in wild bird populations scarcely exceeds 1%. Observing an abnormally colored bird provides insight into intraspecific phenotypic variability as well as how variations persist in nature. How does looking different affect their survival, inter- and intraspecific interactions, mating success, and foraging behaviors? Long-term observations are needed to better understand the ecology of such rare leucistic birds.